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#ifndef _LINUX_NETFS_H#define _LINUX_NETFS_H
#include <linux/workqueue.h>#include <linux/fs.h>#include <linux/pagemap.h>#include <linux/uio.h>#include <linux/rolling_buffer.h>
enum netfs_sreq_ref_trace;typedef struct mempool mempool_t;struct folio_queue;
/** * folio_start_private_2 - Start an fscache write on a folio. [DEPRECATED] * @folio: The folio. * * Call this function before writing a folio to a local cache. Starting a * second write before the first one finishes is not allowed. * * Note that this should no longer be used. */static inline void folio_start_private_2(struct folio *folio){ VM_BUG_ON_FOLIO(folio_test_private_2(folio), folio); folio_get(folio); folio_set_private_2(folio);}
enum netfs_io_source { NETFS_SOURCE_UNKNOWN, NETFS_FILL_WITH_ZEROES, NETFS_DOWNLOAD_FROM_SERVER, NETFS_READ_FROM_CACHE, NETFS_INVALID_READ, NETFS_UPLOAD_TO_SERVER, NETFS_WRITE_TO_CACHE,} __mode(byte);
typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error);
/* * Per-inode context. This wraps the VFS inode. */struct netfs_inode { struct inode inode; /* The VFS inode */ const struct netfs_request_ops *ops;#if IS_ENABLED(CONFIG_FSCACHE) struct fscache_cookie *cache;#endif struct list_head wb_queue; /* Queue of processes wanting to do writeback */ loff_t _remote_i_size; /* Size of the remote file */ loff_t _zero_point; /* Size after which we assume there's no data * on the server */ spinlock_t lock; /* Lock covering wb_queue */ atomic_t io_count; /* Number of outstanding reqs */ unsigned long flags;#define NETFS_ICTX_ODIRECT 0 /* The file has DIO in progress */#define NETFS_ICTX_UNBUFFERED 1 /* I/O should not use the pagecache */#define NETFS_ICTX_WB_LOCK 2 /* Writeback serialisation lock */#define NETFS_ICTX_MODIFIED_ATTR 3 /* Indicate change in mtime/ctime */#define NETFS_ICTX_SINGLE_NO_UPLOAD 4 /* Monolithic payload, cache but no upload */};
/* * A netfs group - for instance a ceph snap. This is marked on dirty pages and * pages marked with a group must be flushed before they can be written under * the domain of another group. */struct netfs_group { refcount_t ref; void (*free)(struct netfs_group *netfs_group);};
/* * Information about a dirty page (attached only if necessary). * folio->private */struct netfs_folio { struct netfs_group *netfs_group; /* Filesystem's grouping marker (or NULL). */ unsigned int dirty_offset; /* Write-streaming dirty data offset */ unsigned int dirty_len; /* Write-streaming dirty data length */};#define NETFS_FOLIO_INFO 0x1UL /* OR'd with folio->private. */#define NETFS_FOLIO_COPY_TO_CACHE ((struct netfs_group *)0x356UL) /* Write to the cache only */
static inline bool netfs_is_folio_info(const void *priv){ return (unsigned long)priv & NETFS_FOLIO_INFO;}
static inline struct netfs_folio *__netfs_folio_info(const void *priv){ if (netfs_is_folio_info(priv)) return (struct netfs_folio *)((unsigned long)priv & ~NETFS_FOLIO_INFO); return NULL;}
static inline struct netfs_folio *netfs_folio_info(struct folio *folio){ return __netfs_folio_info(folio_get_private(folio));}
static inline struct netfs_group *netfs_folio_group(struct folio *folio){ struct netfs_folio *finfo; void *priv = folio_get_private(folio);
finfo = netfs_folio_info(folio); if (finfo) return finfo->netfs_group; return priv;}
/* * Stream of I/O subrequests going to a particular destination, such as the * server or the local cache. This is mainly intended for writing where we may * have to write to multiple destinations concurrently. */struct netfs_io_stream { /* Submission tracking */ struct netfs_io_subrequest *construct; /* Op being constructed */ size_t sreq_max_len; /* Maximum size of a subrequest */ unsigned int sreq_max_segs; /* 0 or max number of segments in an iterator */ unsigned int submit_off; /* Folio offset we're submitting from */ unsigned int submit_len; /* Amount of data left to submit */ unsigned int submit_extendable_to; /* Amount I/O can be rounded up to */ void (*prepare_write)(struct netfs_io_subrequest *subreq); void (*issue_write)(struct netfs_io_subrequest *subreq); /* Collection tracking */ struct list_head subrequests; /* Contributory I/O operations */ unsigned long long collected_to; /* Position we've collected results to */ size_t transferred; /* The amount transferred from this stream */ unsigned short error; /* Aggregate error for the stream */ enum netfs_io_source source; /* Where to read from/write to */ unsigned char stream_nr; /* Index of stream in parent table */ bool avail; /* T if stream is available */ bool active; /* T if stream is active */ bool need_retry; /* T if this stream needs retrying */ bool failed; /* T if this stream failed */ bool transferred_valid; /* T is ->transferred is valid */};
/* * Resources required to do operations on a cache. */struct netfs_cache_resources { const struct netfs_cache_ops *ops; void *cache_priv; void *cache_priv2; unsigned int debug_id; /* Cookie debug ID */ unsigned int inval_counter; /* object->inval_counter at begin_op */};
/* * Descriptor for a single component subrequest. Each operation represents an * individual read/write from/to a server, a cache, a journal, etc.. * * The buffer iterator is persistent for the life of the subrequest struct and * the pages it points to can be relied on to exist for the duration. */struct netfs_io_subrequest { struct netfs_io_request *rreq; /* Supervising I/O request */ struct work_struct work; struct list_head rreq_link; /* Link in rreq->subrequests */ struct iov_iter io_iter; /* Iterator for this subrequest */ unsigned long long start; /* Where to start the I/O */ size_t len; /* Size of the I/O */ size_t transferred; /* Amount of data transferred */ refcount_t ref; short error; /* 0 or error that occurred */ unsigned short debug_index; /* Index in list (for debugging output) */ unsigned int nr_segs; /* Number of segs in io_iter */ u8 retry_count; /* The number of retries (0 on initial pass) */ enum netfs_io_source source; /* Where to read from/write to */ unsigned char stream_nr; /* I/O stream this belongs to */ unsigned long flags;#define NETFS_SREQ_COPY_TO_CACHE 0 /* Set if should copy the data to the cache */#define NETFS_SREQ_CLEAR_TAIL 1 /* Set if the rest of the read should be cleared */#define NETFS_SREQ_MADE_PROGRESS 4 /* Set if we transferred at least some data */#define NETFS_SREQ_BOUNDARY 6 /* Set if ends on hard boundary (eg. ceph object) */#define NETFS_SREQ_HIT_EOF 7 /* Set if short due to EOF */#define NETFS_SREQ_IN_PROGRESS 8 /* Unlocked when the subrequest completes */#define NETFS_SREQ_NEED_RETRY 9 /* Set if the filesystem requests a retry */#define NETFS_SREQ_FAILED 10 /* Set if the subreq failed unretryably */};
enum netfs_io_origin { NETFS_READAHEAD, /* This read was triggered by readahead */ NETFS_READPAGE, /* This read is a synchronous read */ NETFS_READ_GAPS, /* This read is a synchronous read to fill gaps */ NETFS_READ_SINGLE, /* This read should be treated as a single object */ NETFS_READ_FOR_WRITE, /* This read is to prepare a write */ NETFS_UNBUFFERED_READ, /* This is an unbuffered read */ NETFS_DIO_READ, /* This is a direct I/O read */ NETFS_WRITEBACK, /* This write was triggered by writepages */ NETFS_WRITEBACK_SINGLE, /* This monolithic write was triggered by writepages */ NETFS_WRITETHROUGH, /* This write was made by netfs_perform_write() */ NETFS_UNBUFFERED_WRITE, /* This is an unbuffered write */ NETFS_DIO_WRITE, /* This is a direct I/O write */ NETFS_PGPRIV2_COPY_TO_CACHE, /* [DEPRECATED] This is writing read data to the cache */ nr__netfs_io_origin} __mode(byte);
/* * Descriptor for an I/O helper request. This is used to make multiple I/O * operations to a variety of data stores and then stitch the result together. */struct netfs_io_request { union { struct work_struct cleanup_work; /* Deferred cleanup work */ struct rcu_head rcu; }; struct work_struct work; /* Result collector work */ struct inode *inode; /* The file being accessed */ struct address_space *mapping; /* The mapping being accessed */ struct kiocb *iocb; /* AIO completion vector */ struct netfs_cache_resources cache_resources; struct netfs_io_request *copy_to_cache; /* Request to write just-read data to the cache */#ifdef CONFIG_PROC_FS struct list_head proc_link; /* Link in netfs_iorequests */#endif struct netfs_io_stream io_streams[2]; /* Streams of parallel I/O operations */#define NR_IO_STREAMS 2 //wreq->nr_io_streams struct netfs_group *group; /* Writeback group being written back */ struct rolling_buffer buffer; /* Unencrypted buffer */#define NETFS_ROLLBUF_PUT_MARK ROLLBUF_MARK_1#define NETFS_ROLLBUF_PAGECACHE_MARK ROLLBUF_MARK_2 wait_queue_head_t waitq; /* Processor waiter */ void *netfs_priv; /* Private data for the netfs */ void *netfs_priv2; /* Private data for the netfs */ struct bio_vec *direct_bv; /* DIO buffer list (when handling iovec-iter) */ unsigned long long submitted; /* Amount submitted for I/O so far */ unsigned long long len; /* Length of the request */ size_t transferred; /* Amount to be indicated as transferred */ size_t progress_at; /* Report read progress when hit this much read */ long error; /* 0 or error that occurred */ unsigned long long i_size; /* Size of the file */ unsigned long long start; /* Start position */ atomic64_t issued_to; /* Write issuer folio cursor */ unsigned long long collected_to; /* Point we've collected to */ unsigned long long cleaned_to; /* Position we've cleaned folios to */ unsigned long long abandon_to; /* Position to abandon folios to */ const struct folio *no_unlock_folio; /* Don't unlock this folio after read */ gfp_t gfp; /* GFP flags to use */ unsigned int direct_bv_count; /* Number of elements in direct_bv[] */ unsigned int debug_id; unsigned int rsize; /* Maximum read size (0 for none) */ unsigned int wsize; /* Maximum write size (0 for none) */ atomic_t subreq_counter; /* Next subreq->debug_index */ unsigned int nr_group_rel; /* Number of refs to release on ->group */ spinlock_t lock; /* Lock for queuing subreqs */ enum netfs_io_origin origin; /* Origin of the request */ bool direct_bv_unpin; /* T if direct_bv[] must be unpinned */ refcount_t ref; unsigned long flags;#define NETFS_RREQ_IN_PROGRESS 0 /* Unlocked when the request completes (has ref) */#define NETFS_RREQ_ALL_QUEUED 1 /* All subreqs are now queued */#define NETFS_RREQ_PAUSE 2 /* Pause subrequest generation */#define NETFS_RREQ_FAILED 3 /* The request failed */#define NETFS_RREQ_RETRYING 4 /* Set if we're in the retry path */#define NETFS_RREQ_SHORT_TRANSFER 5 /* Set if we have a short transfer */#define NETFS_RREQ_OFFLOAD_COLLECTION 8 /* Offload collection to workqueue */#define NETFS_RREQ_NO_UNLOCK_FOLIO 9 /* Don't unlock no_unlock_folio on completion */#define NETFS_RREQ_CANCEL_CACHING 10 /* Set to cancel caching */#define NETFS_RREQ_UPLOAD_TO_SERVER 11 /* Need to write to the server */#define NETFS_RREQ_USE_IO_ITER 12 /* Use ->io_iter rather than ->i_pages */#define NETFS_RREQ_NEED_PUT_RA_REFS 17 /* Need to put the folio refs RA gave us */#define NETFS_RREQ_USE_PGPRIV2 31 /* [DEPRECATED] Use PG_private_2 to mark * write to cache on read */ const struct netfs_request_ops *netfs_ops;};
/* * Operations the network filesystem can/must provide to the helpers. */struct netfs_request_ops { mempool_t *request_pool; mempool_t *subrequest_pool; int (*init_request)(struct netfs_io_request *rreq, struct file *file); void (*free_request)(struct netfs_io_request *rreq); void (*free_subrequest)(struct netfs_io_subrequest *rreq);
/* Read request handling */ void (*expand_readahead)(struct netfs_io_request *rreq); int (*prepare_read)(struct netfs_io_subrequest *subreq); void (*issue_read)(struct netfs_io_subrequest *subreq); bool (*is_still_valid)(struct netfs_io_request *rreq); int (*check_write_begin)(struct file *file, loff_t pos, unsigned len, struct folio **foliop, void **_fsdata); void (*done)(struct netfs_io_request *rreq);
/* Modification handling */ void (*update_i_size)(struct inode *inode, loff_t i_size); void (*post_modify)(struct inode *inode);
/* Write request handling */ void (*begin_writeback)(struct netfs_io_request *wreq); void (*prepare_write)(struct netfs_io_subrequest *subreq); void (*issue_write)(struct netfs_io_subrequest *subreq); void (*retry_request)(struct netfs_io_request *wreq, struct netfs_io_stream *stream); void (*invalidate_cache)(struct netfs_io_request *wreq);};
/* * How to handle reading from a hole. */enum netfs_read_from_hole { NETFS_READ_HOLE_IGNORE, NETFS_READ_HOLE_FAIL,};
/* * Table of operations for access to a cache. */struct netfs_cache_ops { /* End an operation */ void (*end_operation)(struct netfs_cache_resources *cres);
/* Read data from the cache */ int (*read)(struct netfs_cache_resources *cres, loff_t start_pos, struct iov_iter *iter, enum netfs_read_from_hole read_hole, netfs_io_terminated_t term_func, void *term_func_priv);
/* Write data to the cache */ int (*write)(struct netfs_cache_resources *cres, loff_t start_pos, struct iov_iter *iter, netfs_io_terminated_t term_func, void *term_func_priv);
/* Write data to the cache from a netfs subrequest. */ void (*issue_write)(struct netfs_io_subrequest *subreq);
/* Expand readahead request */ void (*expand_readahead)(struct netfs_cache_resources *cres, unsigned long long *_start, unsigned long long *_len, unsigned long long i_size);
/* Prepare a read operation, shortening it to a cached/uncached * boundary as appropriate. */ enum netfs_io_source (*prepare_read)(struct netfs_io_subrequest *subreq, unsigned long long i_size);
/* Prepare a write subrequest, working out if we're allowed to do it * and finding out the maximum amount of data to gather before * attempting to submit. If we're not permitted to do it, the * subrequest should be marked failed. */ void (*prepare_write_subreq)(struct netfs_io_subrequest *subreq);
/* Prepare a write operation, working out what part of the write we can * actually do. */ int (*prepare_write)(struct netfs_cache_resources *cres, loff_t *_start, size_t *_len, size_t upper_len, loff_t i_size, bool no_space_allocated_yet);
/* Query the occupancy of the cache in a region, returning where the * next chunk of data starts and how long it is. */ int (*query_occupancy)(struct netfs_cache_resources *cres, loff_t start, size_t len, size_t granularity, loff_t *_data_start, size_t *_data_len);};
/* High-level read API. */ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *iter);ssize_t netfs_unbuffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);ssize_t netfs_buffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);ssize_t netfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);
/* High-level write API */ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter, struct netfs_group *netfs_group);ssize_t netfs_buffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *from, struct netfs_group *netfs_group);ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from);ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter, struct netfs_group *netfs_group);ssize_t netfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from);void netfs_clear_stale_post_isize(struct inode *inode, uoff_t from, uoff_t to);
/* Single, monolithic object read/write API. */void netfs_single_mark_inode_dirty(struct inode *inode);ssize_t netfs_read_single(struct inode *inode, struct file *file, struct iov_iter *iter);int netfs_writeback_single(struct address_space *mapping, struct writeback_control *wbc, struct iov_iter *iter);
/* Address operations API */struct readahead_control;void netfs_readahead(struct readahead_control *);int netfs_read_folio(struct file *, struct folio *);int netfs_write_begin(struct netfs_inode *, struct file *, struct address_space *, loff_t pos, unsigned int len, struct folio **, void **fsdata);int netfs_writepages(struct address_space *mapping, struct writeback_control *wbc);bool netfs_dirty_folio(struct address_space *mapping, struct folio *folio);int netfs_unpin_writeback(struct inode *inode, struct writeback_control *wbc);void netfs_clear_inode_writeback(struct inode *inode, const void *aux);void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length);bool netfs_release_folio(struct folio *folio, gfp_t gfp);
/* VMA operations API. */vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group);
/* (Sub)request management API. */void netfs_read_subreq_progress(struct netfs_io_subrequest *subreq);void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq);void netfs_get_subrequest(struct netfs_io_subrequest *subreq, enum netfs_sreq_ref_trace what);void netfs_put_subrequest(struct netfs_io_subrequest *subreq, enum netfs_sreq_ref_trace what);ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len, struct iov_iter *new, iov_iter_extraction_t extraction_flags);size_t netfs_limit_iter(const struct iov_iter *iter, size_t start_offset, size_t max_size, size_t max_segs);void netfs_prepare_write_failed(struct netfs_io_subrequest *subreq);void netfs_write_subrequest_terminated(void *_op, ssize_t transferred_or_error);
int netfs_start_io_read(struct inode *inode);void netfs_end_io_read(struct inode *inode);int netfs_start_io_write(struct inode *inode);void netfs_end_io_write(struct inode *inode);int netfs_start_io_direct(struct inode *inode);void netfs_end_io_direct(struct inode *inode);
/* Miscellaneous APIs. */struct folio_queue *netfs_folioq_alloc(unsigned int rreq_id, gfp_t gfp, unsigned int trace /*enum netfs_folioq_trace*/);void netfs_folioq_free(struct folio_queue *folioq, unsigned int trace /*enum netfs_trace_folioq*/);
/* Buffer wrangling helpers API. */int netfs_alloc_folioq_buffer(struct address_space *mapping, struct folio_queue **_buffer, size_t *_cur_size, ssize_t size, gfp_t gfp);void netfs_free_folioq_buffer(struct folio_queue *fq);
/* Writeback exclusion API. */bool netfs_wb_begin(struct netfs_inode *ictx, bool nowait);void netfs_wb_end(struct netfs_inode *ictx);
/** * netfs_inode - Get the netfs inode context from the inode * @inode: The inode to query * * Get the netfs lib inode context from the network filesystem's inode. The * context struct is expected to directly follow on from the VFS inode struct. */static inline struct netfs_inode *netfs_inode(struct inode *inode){ return container_of(inode, struct netfs_inode, inode);}
/** * netfs_read_remote_i_size - Read remote_i_size safely * @inode: The inode to access * * Read remote_i_size safely without the potential for tearing on 32-bit * arches. * * NOTE: in a 32bit arch with a preemptable kernel and an UP compile the * i_size_read/write must be atomic with respect to the local cpu (unlike with * preempt disabled), but they don't need to be atomic with respect to other * cpus like in true SMP (so they need either to either locally disable irq * around the read or for example on x86 they can be still implemented as a * cmpxchg8b without the need of the lock prefix). For SMP compiles and 64bit * archs it makes no difference if preempt is enabled or not. */static inline unsigned long long netfs_read_remote_i_size(const struct inode *inode){ const struct netfs_inode *ictx = container_of(inode, struct netfs_inode, inode); unsigned long long remote_i_size;
#if BITS_PER_LONG==32 && defined(CONFIG_SMP) unsigned int seq;
do { seq = read_seqcount_begin(&inode->i_size_seqcount); remote_i_size = ictx->_remote_i_size; } while (read_seqcount_retry(&inode->i_size_seqcount, seq));#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) preempt_disable(); remote_i_size = ictx->_remote_i_size; preempt_enable();#else /* Pairs with smp_store_release() in netfs_write_remote_i_size() */ remote_i_size = smp_load_acquire(&ictx->_remote_i_size);#endif return remote_i_size;}
/* * netfs_write_remote_i_size - Set remote_i_size safely * @inode: The inode to access * @remote_i_size: The new value for the size of the file on the server * * Set remote_i_size safely without the potential for tearing on 32-bit arches. * * Context: The caller must hold inode->i_lock. * * NOTE: unlike netfs_read_remote_i_size(), netfs_write_remote_i_size() does * need locking around it (normally i_rwsem), otherwise on 32bit/SMP an update * of i_size_seqcount can be lost, resulting in subsequent i_size_read() calls * spinning forever. */static inline void netfs_write_remote_i_size(struct inode *inode, unsigned long long remote_i_size){ struct netfs_inode *ictx = netfs_inode(inode);
#if BITS_PER_LONG==32 && defined(CONFIG_SMP) write_seqcount_begin(&inode->i_size_seqcount); ictx->_remote_i_size = remote_i_size; write_seqcount_end(&inode->i_size_seqcount);#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) preempt_disable(); ictx->_remote_i_size = remote_i_size; preempt_enable();#else /* * Pairs with smp_load_acquire() in netfs_read_remote_i_size() to * ensure changes related to inode size (such as page contents) are * visible before we see the changed inode size. */ smp_store_release(&ictx->_remote_i_size, remote_i_size);#endif}
/** * netfs_read_zero_point - Read zero_point safely * @inode: The inode to access * * Read zero_point safely without the potential for tearing on 32-bit * arches. * * NOTE: in a 32bit arch with a preemptable kernel and an UP compile the * i_size_read/write must be atomic with respect to the local cpu (unlike with * preempt disabled), but they don't need to be atomic with respect to other * cpus like in true SMP (so they need either to either locally disable irq * around the read or for example on x86 they can be still implemented as a * cmpxchg8b without the need of the lock prefix). For SMP compiles and 64bit * archs it makes no difference if preempt is enabled or not. */static inline unsigned long long netfs_read_zero_point(const struct inode *inode){ struct netfs_inode *ictx = container_of(inode, struct netfs_inode, inode); unsigned long long zero_point;
#if BITS_PER_LONG==32 && defined(CONFIG_SMP) unsigned int seq;
do { seq = read_seqcount_begin(&inode->i_size_seqcount); zero_point = ictx->_zero_point; } while (read_seqcount_retry(&inode->i_size_seqcount, seq));#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) preempt_disable(); zero_point = ictx->_zero_point; preempt_enable();#else /* Pairs with smp_store_release() in netfs_write_zero_point() */ zero_point = smp_load_acquire(&ictx->_zero_point);#endif return zero_point;}
/* * netfs_write_zero_point - Set zero_point safely * @inode: The inode to access * @zero_point: The new value for the point beyond which the server has no data * * Set zero_point safely without the potential for tearing on 32-bit arches. * * Context: The caller must hold inode->i_lock. * * NOTE: unlike netfs_read_zero_point(), netfs_write_zero_point() does need * locking around it (normally i_rwsem), otherwise on 32bit/SMP an update of * i_size_seqcount can be lost, resulting in subsequent read calls spinning * forever. */static inline void netfs_write_zero_point(struct inode *inode, unsigned long long zero_point){ struct netfs_inode *ictx = netfs_inode(inode);
#if BITS_PER_LONG==32 && defined(CONFIG_SMP) write_seqcount_begin(&inode->i_size_seqcount); ictx->_zero_point = zero_point; write_seqcount_end(&inode->i_size_seqcount);#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) preempt_disable(); ictx->_zero_point = zero_point; preempt_enable();#else /* * Pairs with smp_load_acquire() in netfs_read_zero_point() to * ensure changes related to inode size (such as page contents) are * visible before we see the changed inode size. */ smp_store_release(&ictx->_zero_point, zero_point);#endif}
/** * netfs_read_sizes - Read remote_i_size and zero_point safely * @inode: The inode to access * @i_size: Where to return the local file size. * @remote_i_size: Where to return the size of the file on the server * @zero_point: Where to return the the point beyond which the server has no data * * Read remote_i_size and zero_point safely without the potential for tearing * on 32-bit arches. * * NOTE: in a 32bit arch with a preemptable kernel and an UP compile the * i_size_read/write must be atomic with respect to the local cpu (unlike with * preempt disabled), but they don't need to be atomic with respect to other * cpus like in true SMP (so they need either to either locally disable irq * around the read or for example on x86 they can be still implemented as a * cmpxchg8b without the need of the lock prefix). For SMP compiles and 64bit * archs it makes no difference if preempt is enabled or not. */static inline void netfs_read_sizes(const struct inode *inode, unsigned long long *i_size, unsigned long long *remote_i_size, unsigned long long *zero_point){ const struct netfs_inode *ictx = container_of(inode, struct netfs_inode, inode);#if BITS_PER_LONG==32 && defined(CONFIG_SMP) unsigned int seq;
do { seq = read_seqcount_begin(&inode->i_size_seqcount); *i_size = inode->i_size; *remote_i_size = ictx->_remote_i_size; *zero_point = ictx->_zero_point; } while (read_seqcount_retry(&inode->i_size_seqcount, seq));#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) preempt_disable(); *i_size = inode->i_size; *remote_i_size = ictx->_remote_i_size; *zero_point = ictx->_zero_point; preempt_enable();#else /* Pairs with smp_store_release() in i_size_write() */ *i_size = smp_load_acquire(&inode->i_size); /* Pairs with smp_store_release() in netfs_write_remote_i_size() */ *remote_i_size = smp_load_acquire(&ictx->_remote_i_size); /* Pairs with smp_store_release() in netfs_write_zero_point() */ *zero_point = smp_load_acquire(&ictx->_zero_point);#endif}
/* * netfs_write_sizes - Set i_size, remote_i_size and zero_point safely * @inode: The inode to access * @i_size: The new value for the local size of the file * @remote_i_size: The new value for the size of the file on the server * @zero_point: The new value for the point beyond which the server has no data * * Set both remote_i_size and zero_point safely without the potential for * tearing on 32-bit arches. * * Context: The caller must hold inode->i_lock. * * NOTE: unlike netfs_read_zero_point(), netfs_write_zero_point() does need * locking around it (normally i_rwsem), otherwise on 32bit/SMP an update of * i_size_seqcount can be lost, resulting in subsequent read calls spinning * forever. */static inline void netfs_write_sizes(struct inode *inode, unsigned long long i_size, unsigned long long remote_i_size, unsigned long long zero_point){ struct netfs_inode *ictx = netfs_inode(inode);
#if BITS_PER_LONG==32 && defined(CONFIG_SMP) write_seqcount_begin(&inode->i_size_seqcount); inode->i_size = i_size; ictx->_remote_i_size = remote_i_size; ictx->_zero_point = zero_point; write_seqcount_end(&inode->i_size_seqcount);#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) preempt_disable(); inode->i_size = i_size; ictx->_remote_i_size = remote_i_size; ictx->_zero_point = zero_point; preempt_enable();#else /* * Pairs with smp_load_acquire() in i_size_read(), * netfs_read_remote_i_size() and netfs_read_zero_point() to ensure * changes related to inode size (such as page contents) are visible * before we see the changed inode size. */ smp_store_release(&inode->i_size, i_size); smp_store_release(&ictx->_remote_i_size, remote_i_size); smp_store_release(&ictx->_zero_point, zero_point);#endif}
/** * netfs_inode_init - Initialise a netfslib inode context * @ctx: The netfs inode to initialise * @ops: The netfs's operations list * @use_zero_point: True to use the zero_point read optimisation * * Initialise the netfs library context struct. This is expected to follow on * directly from the VFS inode struct. */static inline void netfs_inode_init(struct netfs_inode *ctx, const struct netfs_request_ops *ops, bool use_zero_point){ ctx->ops = ops; ctx->_remote_i_size = i_size_read(&ctx->inode); ctx->_zero_point = LLONG_MAX; ctx->flags = 0; atomic_set(&ctx->io_count, 0);#if IS_ENABLED(CONFIG_FSCACHE) ctx->cache = NULL;#endif INIT_LIST_HEAD(&ctx->wb_queue); spin_lock_init(&ctx->lock); /* ->releasepage() drives zero_point */ if (use_zero_point) { ctx->_zero_point = ctx->_remote_i_size; mapping_set_release_always(ctx->inode.i_mapping); }}
/** * netfs_resize_file - Note that a file got resized * @ictx: The netfs inode being resized * @new_i_size: The new file size * @changed_on_server: The change was applied to the server * * Inform the netfs lib that a file got resized so that it can adjust its state. */static inline void netfs_resize_file(struct netfs_inode *ictx, unsigned long long new_i_size, bool changed_on_server){#if BITS_PER_LONG==32 && defined(CONFIG_SMP) struct inode *inode = &ictx->inode;
preempt_disable(); write_seqcount_begin(&inode->i_size_seqcount); if (changed_on_server) ictx->_remote_i_size = new_i_size; if (new_i_size < ictx->_zero_point) ictx->_zero_point = new_i_size; write_seqcount_end(&inode->i_size_seqcount); preempt_enable();#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) preempt_disable(); if (changed_on_server) ictx->_remote_i_size = new_i_size; if (new_i_size < ictx->_zero_point) ictx->_zero_point = new_i_size; preempt_enable();#else /* * Pairs with smp_load_acquire() in netfs_read_remote_i_size and * netfs_read_zero_point() to ensure changes related to inode size * (such as page contents) are visible before we see the changed inode * size. */ if (changed_on_server) smp_store_release(&ictx->_remote_i_size, new_i_size); if (new_i_size < ictx->_zero_point) smp_store_release(&ictx->_zero_point, new_i_size);#endif}
/** * netfs_i_cookie - Get the cache cookie from the inode * @ctx: The netfs inode to query * * Get the caching cookie (if enabled) from the network filesystem's inode. */static inline struct fscache_cookie *netfs_i_cookie(struct netfs_inode *ctx){#if IS_ENABLED(CONFIG_FSCACHE) return ctx->cache;#else return NULL;#endif}
/** * netfs_wait_for_outstanding_io - Wait for outstanding I/O to complete * @inode: The netfs inode to wait on * * Wait for outstanding I/O requests of any type to complete. This is intended * to be called from inode eviction routines. This makes sure that any * resources held by those requests are cleaned up before we let the inode get * cleaned up. */static inline void netfs_wait_for_outstanding_io(struct inode *inode){ struct netfs_inode *ictx = netfs_inode(inode);
wait_var_event(&ictx->io_count, atomic_read(&ictx->io_count) == 0);}
#endif /* _LINUX_NETFS_H */